NaYF4:Yb, Er/NaYF4 core-shell nanocrystals with different thickness shells were synthesized. The correlation between shell thickness and upconversion (UC) luminescence intensity was investigated experimentally and theoretically. We found that the UC fluorescence intensity of the core-shell nanocrystals is enhanced exponentially with shell thickness (d) in the form of (1-0.9 exp(-d/d0). For our ...

The optimal distribution of the reinforcing fibers for stiffening hollow cylindrical composites is explored using the linear elasticity theory. The spatial distribution of the vascular bundles in wild bamboo, a nature-designed functionally graded material, is the basis for the design. Our results suggest that wild bamboos maximize their flexural rigidity by optimally regulating the radial grada...

A new method for obtaining the response of a baaed, uid{loaded, nite cylindrical shell using the nite element method is presented. The Galerkin nite element formulation for this problem utilizes a Neumann Green's function representation of the pressure loading on the shell. By representing the pressure loading in this manner, only the structure need be discretized. Both C 0 and C 1 nite element...

Cylindrical shells, unstiffened or stiffened with rings and/or stringers are commonly used in offshore structures as main loading-carrying members. Comprehensive theoretical work and experimental studies on the buckling behavior of cylindrical shells have been carried out in the past. The increasing offshore application of stiffened cylindrical shells has raised some new challenges that need to...

The problem of a point force acting in an unbounded, three-dimensional, isotropic elastic solid is considered. Kelvin solved this problem for homogeneous materials. Here, the material is inhomogeneous; it is ‘functionally graded’. Specifically, the solid is ‘exponentially graded’, which means that the Lamé moduli vary exponentially in a given fixed direction. The solution for the Green’s functi...

In this study, the free vibration of partially fluid-filled laminated composite circular cylindrical shell with arbitrary boundary conditions has been investigated by using Rayleigh-Ritz method. The analysis has been carried out with strain-displacement relations based on Love’s thin shell theory and the contained fluid is assumed irrotational, incompressible and inviscid. After determining the...

For cylindrical shell gyroscopes, node position of their operating eigenmodes has an important influence on the gyroscopes' performance. It is considered that the nodes are equally separated from each other by 90° when the resonator vibrates in the standing wave eigenmode. However, we found that, due to manufacturing errors and trimming, the nodes may not be equally distributed. This paper main...

The paper introduces a new alternative towards fabrication of auxetic metamaterials (materials with negative Poisson’s ratio) controlled by geometric transformations. These transformations are derived from the theory of small (infinitesimal) elastic deformation superimposed on finite elastic deformations. By using this theory, a cylindrical region filled with initial deformed foam is transforme...

We investigate the twofold functionality of a cylindrical shell consisting of a negatively refracting heterogeneous bianisotropic (NRHB) medium deduced from geometric transforms. The numerical simulations indicate that the shell enhances their scattering by a perfect electric conducting (PEC) core, whereas it considerably reduces the scattering of electromagnetic waves by closely located object...

based on three-dimensional theory of elasticity, static analysis of functionally graded carbon nanotube reinforced composite (fg-cntrc) cylindrical panel subjected to mechanical uniformed load with simply supported boundary conditions is carried out. in the process, stress and displacement fields are expanded according to the fourier series along the axial and circumferential coordinates. from ...